1. FIELD OF THE INVENTION
This invention relates to a yarn of thermoplastic synthetic fibers which resembles a spun yarn. In particular, the invention relates to a novel spinning process, and more specifically, to a process for producing a spun yarn-like yarn (sometimes to be referred to hereinafter simply as a "spun-like yarn") from insufficiently oriented fibers of a thermoplastic polymer directly in a substantially single step.
2. DESCRIPTION OF THE PRIOR ART
Processes for obtaining spun yarns from synthetic fibers are roughly classified into a group of processes using broken fibers, that is staple fibers, and another group of processes using filament yarns such as tows. The former group includes, for example, cotton, worsted, and silk spinning methods. A suitable spinning process is chosen depending on the length of the staple fibers used and the end use of the spun yarn, and when spinning synthetic fibers, the number of the steps is reduced or the time required for a particular step is shortened, as compared with the case of using natural fibers such as cotton or wool. Since the staple fibers used in these processes are in a compressed bale form and the directions of the individual fibers are quite at random, the spinning process using the staple fibers first involves opening the staple fibers to orient them in the same direction and to form a sliver, drafting it repeatedly while aligning the individual fibers to increase the directionality and uniformity of the fibers, and finally twisting the drafted sliver thereby to impart the tenacity required of a yarn due to the frictional force between the individual staple fibers and thus to form a spun yarn. This means that the spun yarn is obtained after going through several intermittent steps. Furthermore, the several steps in this process involve a different amount of products, so that very complicated equipment is required in order to combine these steps into a single continuous spinning process. Sufficient measures should also be taken to cope with any difficulties that may occur in each of the steps and to control and maintain the apparatus.
The latter group of spinning processes using filament yarns is divided into a staple method (the Perlok system, the Turbo Stapler system, or the direct spinning system) which comprises drafting a tow of drawn fibers further between draft rolls and breaking the tow to form continuous slivers, and a converter method which comprises obliquely breaking a tow of fibers spread and paralleled, and then intertwining the broken tows into a continuous sliver. Except for the direct spinning system, in such a process also, the tows are first converted to slivers, and a spun yarn is produced through several drafting steps. In the latter half of the process, the same steps as used in the spinning process using staple fibers must be performed. In the direct spinning system, no new step is required after drafting and breaking the filaments to form slivers. However, the unevenness in the slivers formed due to a slight unevenness in tenacity and elongation of the tow and the unevenness in the fiber length arising from the tow are further promoted at the time of drafting, and therefore, in order to obtain uniform yarns, the tow must have a considerably high quality level.
In contrast to these conventional spinning processes, the present invention involves a simplification and improvements of efficiency of the entire spinning process.